The use of color cosmetics dates back to the times of the Egyptians. The adornment of the skin and more particularly, the lips with color has been important to humans for many centuries. A particular difficulty that is encountered with the use of pigmented products on the lips is the fact that the lips are in intimate contact with the tongue and taste is a major consideration as to weather a particular product is used on the lips.
Lipsticks are made up of a variety of materials that are combined to make the delivery of color to the lips. The formulations contain waxes, silicone resin, organic esters, pigments and other additives. The difference in solubility of these materials cause a problem called syneresis, a “bleeding” of a liquid phase from the wax phase. Additives like esters are used to minimize the occurrence of syneresis.
Unfortunately, since organic esters are made at elevated temperatures of compounds that have a tendency to oxidize, producing aldehydic and ketonic bodies that condense can contribute bad taste to these compounds.